1. Field of the Invention
The present invention relates generally to spark plugs and, more particulary to spark plugs having an electrode that facilitates propagation of a burn front.
2. Description of the Background
The subject matter disclosed herein relates to a spark plug for use with an internal combustion engine, and more particularly to a spark plug having a structure providing improved flame kernel development.
Conventional spark plugs for use in internal combustion engines generally include a tube-shaped metallic shell, an insulator, a center electrode and a ground electrode. The metal shell has a threaded portion for fitting the spark plug into a combustion chamber for the engine. The insulator has a center bore formed therein and is fixed in the metal shell such that an end of the insulator protrudes from the end of the metal shell. The center electrode is positioned within the center bore of the insulator and protrudes outwardly of the insulator. The ground electrode has a first end that is joined to an end of the metal shell and curves such that a second end including a tip portion faces an end of the center electrode to create a gap.
The gap between the end of the center electrode and the tip portion of the ground electrode is generally perpendicular to the axis of the spark plug. As a result, the direction of the burn front is limited, at least initially, in a sideways direction relative to the spark plug axis. The burn front must travel around the ground electrode structure, which slows the speed of the burn front. Further, this movement also draws thermal energy from the burn front, which could be used to keep the burn front ignited and expanding.
Accordingly, while existing spark plugs are suitable for their intended purposes, the need for improvement remains, particularly in providing a spark plug with an electrode structure that facilitates propagation of the burn front.